Prudence just seen your post on the other thread- great that it looks as if you are making progress.
HRT doesn't 'stop osteoporosis' in its tracks (Beaufort) but the research papers show that most women find their bone density increases by around 2-3% per year using HRT. So, depending on how low the bone density is to start with, this may prevent osteoporosis in some women with osteopenia, or may help women with osteoporosis who can't take other drugs. It depends on your T score.
This is link is from 'Climeratic' the International Menopause Society's journal and written by Prof Studd, a UK expert on menopause.
www.ncbi.nlm.nih.gov/pubmed/19437196
The main points are these:
"A case is made for estrogens to be the first-choice therapy for the prevention and treatment of osteoporosis in women below the age of 60 years.
Estrogens produce a dose-related increase in bone density and also, by their effect on collagen, have a beneficial effect not only on the bone matrix but the intravertebral disc.
Bisphosphonates do not have that effect upon the disc.
Estrogens are also associated with other beneficial effects upon mood, vasomotor symptoms, pelvic atrophy, sexuality and quality of life.
The data from the Women's Health Initiative (WHI) study are used as a justification for not using estrogens but the neglect of estrogen therapy by physicians antedated this and other studies by many years. Subsequent publications from the WHI study show that hormone replacement therapy, particularly estrogens alone, is not associated with the excess side-effects found in the older population.
The substantial but non-significant decrease in heart attacks, breast cancer and mortality in women under the age of 60 taking estrogens alone should persuade the advisory bodies to revise their judgment on the benefits and safety of hormone replacement therapy in this population."